Chicken sandwiches are going into battle
American military researchers have cooked up an indestructible sandwich for soldiers to eat on the battlefield.
It is designed to stay fresh and dry for up to three years, and to withstand airdrops, rough handling and extreme climates.
Until now, American soldiers have been forced to construct their own sandwiches from pasteurised ingredients stored in separate pouches.
But thanks to the indestructible snack, they will now be able to eat on the move.
Project officer Michelle Richardson sampled three-year-old sandwiches and described them as "ok".
"They're not as tasty as the ones that are fresh out of the oven, but they're very highly acceptable," she told the BBC's Today programme.
To combat sogginess, researchers at the US Army Soldier Systems Center in Natick, Massachusetts used fillings such as pepperoni and chicken, then added substances called humectants which prevent water from leaking out.
Humectants also limit the amount of moisture available for bacterial growth.
Battling yeast
Oxygen-scavenging chemicals prevent yeast from growing in the sealed plastic sandwich pouches.
Soldiers who tried the pepperoni and barbecue-chicken "pocket sandwich" have given it their approval, New Scientist magazine reported.
Researchers hope to extend the menu of indestructible edibles to include pocket pizzas, cream-filled bagels, breakfast burritos and peanut butter sandwiches.
New Scientist wrote: "The pocket sandwiches won't see action until 2004. But like dehydrated egg, freeze-dried coffee and processed cheese - all originally developed by the military - the long-life sandwich will probably find its way into grocery stores."